Add Wallet.getBloomFilter and a test-case for it.

core/src/main/java/com/google/bitcoin/core/Wallet.java

@@ -239,6 +239,13 @@ public class Wallet implements Serializable, BlockChainListener {
         return new ArrayList<ECKey>(keychain);
     }
     
+    /**
+     * Returns the number of keys in the keychain.
+     */
+    public synchronized int getKeychainSize() {
+        return keychain.size();
+    }
+
     private synchronized void saveToFile(File temp, File destFile) throws IOException {
         // This odd construction exists to allow Android apps to control file permissions on the newly saved files
         // created by the auto save thread. Android does not respect the standard Java file permission APIs in all
@@ -2204,4 +2211,64 @@ public class Wallet implements Serializable, BlockChainListener {
     public void setLastBlockSeenHash(Sha256Hash lastBlockSeenHash) {
         this.lastBlockSeenHash = lastBlockSeenHash;
     }
+    
+    /**
+     * Gets the number of elements that will be added to a bloom filter returned by getBloomFilter
+     */
+    public int getBloomFilterElementCount() {
+        int size = getKeychainSize() * 2;
+        for (Transaction tx : getTransactions(false, true)) {
+            for (TransactionOutput out : tx.getOutputs()) {
+                try {
+                    if (out.isMine(this) && out.getScriptPubKey().isSentToRawPubKey())
+                        size++;
+                } catch (ScriptException e) {
+                    throw new RuntimeException(e); // If it is ours, we parsed the script corectly, so this shouldn't happen
+                }
+            }
+        }
+        return size;
+    }
+    
+    /**
+     * Gets a bloom filter that contains all of the public keys from this wallet,
+     * and which will provide the given false-positive rate.
+     * 
+     * See the docs for {@link BloomFilter#BloomFilter(int, double)} for a brief explanation of anonymity when using bloom filters.
+     */
+    public BloomFilter getBloomFilter(double falsePositiveRate) {
+        return getBloomFilter(getBloomFilterElementCount(), falsePositiveRate, new Random().nextLong());
+    }
+    
+    /**
+     * Gets a bloom filter that contains all of the public keys from this wallet,
+     * and which will provide the given false-positive rate if it has size elements.
+     * Keep in mind that you will get 2 elements in the bloom filter for each key in the wallet.
+     * 
+     * This is used to generate a BloomFilter which can be #{link BloomFilter.merge}d with another.
+     * It could also be used if you have a specific target for the filter's size.
+     * 
+     * See the docs for {@link BloomFilter#BloomFilter(int, double)} for a brief explanation of anonymity when using bloom filters.
+     */
+    public synchronized BloomFilter getBloomFilter(int size, double falsePositiveRate, long nTweak) {
+        BloomFilter filter = new BloomFilter(size, falsePositiveRate, nTweak);
+        for (ECKey key : keychain) {
+            filter.insert(key.getPubKey());
+            filter.insert(key.getPubKeyHash());
+        }
+        for (Transaction tx : getTransactions(false, true)) {
+            for (int i = 0; i < tx.getOutputs().size(); i++) {
+                TransactionOutput out = tx.getOutputs().get(i);
+                try {
+                    if (out.isMine(this) && out.getScriptPubKey().isSentToRawPubKey()) {
+                        TransactionOutPoint outPoint = new TransactionOutPoint(params, i, tx);
+                        filter.insert(outPoint.bitcoinSerialize());
+                    }
+                } catch (ScriptException e) {
+                    throw new RuntimeException(e); // If it is ours, we parsed the script corectly, so this shouldn't happen
+                }
+            }
+        }
+        return filter;
+    }
 }

core/src/test/java/com/google/bitcoin/core/BloomFilterTest.java

@@ -44,4 +44,32 @@ public class BloomFilterTest {
         // Value generated by the reference client
         assertTrue(Arrays.equals(Hex.decode("03ce42990500000001000080"), filter.bitcoinSerialize()));
     }
+
+    @Test
+    public void walletTest() throws Exception {
+        NetworkParameters params = NetworkParameters.prodNet();
+
+        DumpedPrivateKey privKey = new DumpedPrivateKey(params, "5Kg1gnAjaLfKiwhhPpGS3QfRg2m6awQvaj98JCZBZQ5SuS2F15C");
+        
+        Address addr = privKey.getKey().toAddress(params);
+        assertTrue(addr.toString().equals("17Wx1GQfyPTNWpQMHrTwRSMTCAonSiZx9e"));
+        
+        Wallet wallet = new Wallet(params);
+        // Check that the wallet was created with no keys
+        // If wallets ever get created with keys, this test needs redone.
+        for (ECKey key : wallet.getKeys())
+            fail();
+        wallet.addKey(privKey.getKey());
+        // Add a random key which happens to have been used in a recent generation
+        wallet.addKey(new ECKey(null, Hex.decode("03cb219f69f1b49468bd563239a86667e74a06fcba69ac50a08a5cbc42a5808e99")));
+        wallet.commitTx(new Transaction(params, Hex.decode("01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0d038754030114062f503253482fffffffff01c05e559500000000232103cb219f69f1b49468bd563239a86667e74a06fcba69ac50a08a5cbc42a5808e99ac00000000")));
+        
+        // We should have 2 per pubkey, and one for the pay-2-pubkey output we have
+        assertTrue(wallet.getBloomFilterElementCount() == 5);
+        
+        BloomFilter filter = wallet.getBloomFilter(wallet.getBloomFilterElementCount(), 0.001, 0);
+        
+        // Value generated by the reference client
+        assertTrue(Arrays.equals(Hex.decode("082ae5edc8e51d4a030800000000000000"), filter.bitcoinSerialize()));
+    }
 }